Adsorptive Stripping Voltammetry for Trace Determination of Quinalphos Employing Silicon Carbide Nanoparticles Modified Glassy Carbon Electrode

Copper Oxide Anchored Carbon Nanofibers: A Versatile Platform for Multiplex Detection of Antibiotics, Heavy Metals and Pesticides

Electrochemical sensors offer promising prospects for real-time pollutant monitoring. In this study, copper oxide-dispersed graphitic carbon nanofibers (CuO-CNFs) grown via chemical vapour deposition were employed as a robust platform for detecting a variety of environmental pollutants. This array-based sensor adeptly identifies three different classes of analytes, i. e., antibiotics (chloramphenicol (CP) and tylosin tartrate (TT)), heavy metals (cadmium (Cd) and lead (Pb)), and pesticides (quinalphos (QP) and imidacloprid (IP)). Electron collection is facilitated by a glassy carbon electrode, while various physico-electrochemical methods delve into the properties of CuO-CNFs. The CuO-CNF-modified GCE array rapidly discerns (<15 sec) a broad linear range: 1-20 ppm for CP, 1-13.33 ppm for TT, 0.66-11.66 ppm for Cd, 20-33.33 ppm for Pb, 1.6-11.6 ppm for QP, and 5-25 ppm for IP, boasting quantification limits of 1.0, 1.0, 0.66, 20.0, 1.6, and 5.0 ppm for CP, TT, Cd, Pb, QP, and IP, respectively. Notably, this sensor achieves simultaneous identification of mixed analytes, including CP and TT, Cd and Pb, and QP and IP, within real tap water. Furthermore, the electrochemical sensor exhibits robustness; heightened sensitivity, selectivity, and stability; a swift response; and impressive reproducibility in detecting CP, TT, Cd, Pb, QP, and IP within aqueous samples. Consequently, this array-based electrochemical sensor has emerged as a rapid and simultaneous detection tool for diverse pollutant residues in surface and groundwater samples.

Development and Characterization of Nano-Ink from Silicon Carbide/Multi-Walled Carbon Nanotubes/Synthesized Silver Nanoparticles for Non-Enzymatic Paraoxon Residuals Detection

The ongoing advancement in the synthesis of new nanomaterials has accelerated the rapid development of non-enzymatic pesticide sensors based on electrochemical platforms. This study aims to develop and characterize Nano-ink for applying organophosphorus pesticides using paraoxon residue detection. Multi-walled carbon nanotubes, silicon carbide, and silver nanoparticles were used to create Nano-ink using a green synthesis process in 1:1:0, 1:1:0.5, and 1:1:1 ratios, respectively. These composites were combined with chitosan of varying molecular weights, which served as a stabilizing glue to keep the Nano-ink employed in a functioning electrode stable. By using X-ray powder diffraction, Raman spectroscopy, energy dispersive X-ray spectroscopy, and a field emission scanning electron microscope, researchers were able to examine the crystallinity, element composition, and surface morphology of Nano-ink. The performance of the proposed imprinted working electrode Nano-ink was investigated using cyclic voltammetry and differential pulse voltammetry techniques. The Cyclic voltammogram of Ag NPs/chitosan (medium, 50 mg) illustrated high current responses and favorable conditions of the Nano-ink modified electrode. Under the optimized conditions, the reduction currents of paraoxon using the DPV techniques demonstrated a linear reaction ranging between 0.001 and 1.0 µg/mL (R2 = 0.9959) with a limit of detection of 0.0038 µg/mL and a limit of quantitation of 0.011 µg/mL. It was concluded that the fabricated Nano-ink showed good electrochemical activity for non-enzymatic paraoxon sensing.

Sensors Applied for the Detection of Pesticides and Heavy Metals in Freshwaters

Water is essential for every life living on the planet. However, we are facing a more serious situation such as water pollution since the industrial revolution. Fortunately, many efforts have been done to alleviate/restore water quality in freshwaters. Numerous sensors have been developed to monitor the dynamic change of water quality for ecological, early warning, and protection reasons. In the present review, we briefly introduced the pollution status of two major pollutants, i.e., pesticides and heavy metals, in freshwaters worldwide. Then, we collected data on the sensors applied to detect the two categories of pollutants in freshwaters. Special focuses were given on the sensitivity of sensors indicated by the limit of detection (LOD), sensor types, and applied waterbodies. Our results showed that most of the sensors can be applied for stream and river water. The average LOD was72.53±12.69 ng/ml (n=180) for all pesticides, which is significantly higher than that for heavy metals (65.36±47.51 ng/ml,n=117). However, the LODs of a considerable part of pesticides and heavy metal sensors were higher than the criterion maximum concentration for aquatic life or the maximum contaminant limit concentration for drinking water. For pesticide sensors, the average LODs did not differ among insecticides (63.83±17.42 ng/ml,n=87), herbicides (98.06±23.39 ng/ml,n=71), and fungicides (24.60±14.41 ng/ml,n=22). The LODs that differed among sensor types with biosensors had the highest sensitivity, while electrochemical optical and biooptical sensors showed the lowest sensitivity. The sensitivity of heavy metal sensors varied among heavy metals and sensor types. Most of the sensors were targeted on lead, cadmium, mercury, and copper using electrochemical methods. These results imply that future development of pesticides and heavy metal sensors should (1) enhance the sensitivity to meet the requirements for the protection of aquatic ecosystems and human health and (2) cover more diverse pesticides and heavy metals especially those toxic pollutants that are widely used and frequently been detected in freshwaters (e.g., glyphosate, fungicides, zinc, chromium, and arsenic).